Conventional ignition systems typically apply firing potentials to their engine cylinders in a sequential manner. That is, only one cylinder at a time receives a firing potential, particularly with engines that have more than two cylinders.
Some two cylinder engines that have a carbureted fuel/air intake use a simplified ignition system which applies a firing potential to both cylinders simultaneously. This simplification is possible because, with just two cylinders, only the correct cylinder will actually experience combustion; the spark plug for the other cylinder will spark, but no combustion will occur due to the lack of a combustible fuel/air mixture therein. This permits the use of a more simple ignition system, including the absence of a distributor. However, the simplified ignition system has not been used to apply a firing potential to three or more cylinders simultaneously because at least two of the cylinders would be likely to contain combustible fuel/air mixtures at the same time.